80% engine response in last 10% throttle movement

[Chipmunk]

I'd appreciate any advise on the problem I am experiencing with my throttle control.

I bought a 2003 Tornado 5.4 RIB with a 115 Johnson 2S last year. Even after replacing the throttle cables I find the boat difficult to control as 80% of the power results from the last 10% of the throttle movement - which is also very stiff (presumably as it's opening most of the throttle over that short movement) - and I am wondering whether the throttle control is wrong for the engine. The throttle appears to have an asymmetrical cam which is causing this uneven throttle response. I do understand the rationale behind an asymmetrical throttle (finer throttle control for lower engine speeds) however is it possible that the profile of the cam is wrong for the 115hp engine?

Has anyone else had this problem and if so how did you fix it?

[Pikey Dave]

Originally Posted by Chipmunk

I'd appreciate any advise on the problem I am experiencing with my throttle control.



I bought a 2003 Tornado 5.4 RIB with a 115 Johnson 2S last year. Even after replacing the throttle cables I find the boat difficult to control as 80% of the power results from the last 10% of the throttle movement - which is also very stiff (presumably as it's opening most of the throttle over that short movement) - and I am wondering whether the throttle control is wrong for the engine. The throttle appears to have an asymmetrical cam which is causing this uneven throttle response. I do understand the rationale behind an asymmetrical throttle (finer throttle control for lower engine speeds) however is it possible that the profile of the cam is wrong for the 115hp engine?



Has anyone else had this problem and if so how did you fix it?

How does the throttle cable attach to the carburettor? Sometimes there is a lever with 2 or 3 holes that give a different “throw” depending on which hole is used.

[Chipmunk]

Originally Posted by Pikey Dave

How does the throttle cable attach to the carburettor? Sometimes there is a lever with 2 or 3 holes that give a different “throw” depending on which hole is used.

Thanks. I've checked the linkage but I can't see any options to change the throttle profile. The throttle remote control however is old so I have ordered a new one in the hope this will provide a smoother operation and make it easier to control.

[Peter_C]

Sounds like it needs the cables adjusted.

[Chipmunk]

Originally Posted by Peter_C

Sounds like it needs the cables adjusted.

Yes I did wonder about that. I need to remove the engine casings to get to the throttle connection so I will do that when I get the new remote control.